SpringMVC笔记#

MyBatis#

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--    <settings>-->
    <!--        <setting name="logImpl" value="STDOUT_LOGGING"/>-->
    <!--    </settings>-->
    <environments default="dev">
        <environment id="dev">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm?useSSL=false&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="654321"/>
            </dataSource>
        </environment>

    </environments>
    <mappers>
        <!--        用于编写SQL语句的文件-->
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="userMapper">
    <select id="selectById" resultType="com.bean.User">
        select * from user where `id` = #{id};
    </select>
    <insert id="insertUser">
        insert into user values (#{id}, #{password}, #{balance});
    </insert>
</mapper>

Dao#

写的很简陋，将异常处理之类的都暂时省略

@Repository("userDaoImpl")
public class UserDaoImpl implements UserDao {
    @Override
    public User getUserById(Integer id) {
        SqlSession sqlSession = SqlSessionUtil.getSqlSession();
        Object object = sqlSession.selectOne("selectById", id);
        return (User) object;
    }

    @Override
    public int insertUser(User user) {
        SqlSession sqlSession = SqlSessionUtil.getSqlSession();
        int i = sqlSession.insert("insertUser", user);
        if (i > 0) {
            sqlSession.commit();
        } else {
            sqlSession.rollback();
        }
        return i;
    }
}

Utils#

package com.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;

public class SqlSessionUtil {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            sqlSessionFactory = new SqlSessionFactoryBuilder()
                    .build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private SqlSessionUtil() {}
    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }
}

Cotroller#

在整合使用的时候，Spring的使用需要jdk17版本，而且@PathVariable(“id”)需要显式的指定参数名称

@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserDao userDao;

    @GetMapping("{id}")
    public User getUserById(@PathVariable("id") Integer id) {
        return userDao.getUserById(id);
    }

    @PostMapping
    public String insertUser(@RequestBody User user) {
        int update = userDao.insertUser(user);
        return "success update line:" + update;
    }
}

入门使用#

在表现层新建一个ProjectInterceptor类实现HandlerInterceptor接口

package com.controller;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Component
public class ProjectInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle");
        return true;
        //这里返回false代表终止原始操作，之后的postHandleafter  Completion也不会执行
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }
}

配置SpringMvcSupport，添加重写方法，注入刚才编写的ProjectInterceptor，将类传入addInterceptor方法中，在调用addPathPatterns设置拦截路径

/**为所有的子路径

/*为一级子路径

没有通配符只匹配精确路径

@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Autowired
    private ProjectInterceptor projectInterceptor;
    
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptor).addPathPatterns("/users/**");
    }
}

输出结果

preHandle //原始操作之前的代码
postHandle//原始操作之后的代码
afterCompletion//post之后的代码

简化配置#

通过SpringMvcConfig配置类继承于WebMvcConfigurer接口，重写addInterceptors方法，即可简化实现，再扫描的时候不需要扫描config软件包下SpringMvcSupport

@Configuration
@ComponentScan({"com.controller"})
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {
    @Autowired
    private ProjectInterceptor projectInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptor).addPathPatterns("/users/**");
    }
}

这种方式相较而言简便但是有缺陷，会和Spring强制绑定

拦截器参数#

HttpServletRequest request, HttpServletResponse response,

Object handler通过方法传入的参数可以从其中取出数据，其中handler是方法的对象

ModelAndView modelAndView 其中封装了页面跳转的一些方法供以处理

Exception ex 是异常信息，而我们在使用的时候一般使用异常处理器完成，而不用这个

其中最常用的是preHandle，通过参数做校验，判断是否继续执行后续方法

拦截链配置#

@Configuration
@ComponentScan({"com.controller"})
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {
    @Autowired
    private ProjectInterceptor projectInterceptor;
    @Autowired
    private AnotherInterceptor anotherInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptor).addPathPatterns("/users/**");
        registry.addInterceptor(anotherInterceptor).addPathPatterns("/users/**");
    }
}

preHandle
another preHandle
another postHandle
postHandle
another afterCompletion
afterCompletion

顺序和添加的拦截器顺序有关

registry.addInterceptor(projectInterceptor).addPathPatterns("/users/**");
        registry.addInterceptor(anotherInterceptor).addPathPatterns("/users/**");

前处理器按配置先后执行，而后处理器反向执行

以下是当preHandle返回false的时候的处理顺序，总的来说就是先返回true后的afterCompletion无论如何后续拦截器preHandle返回false与否都要执行先前afterCompletion方法